The present invention relates to video and audio compression technology, and more particularly to an MPEG-2 transport stream multiplexer for combining program elementary video and audio streams consisting of one or more programs such that no processor-based copying is necessary and all data movement is performed by direct memory access (DMA).
Valid MPEG-2 Transport Streams are fully defined by the International Standard ISO/IEC 13818-1, Generic Coding of Moving Pictures and Associated Audio: Systems (11/94). An MPEG-2 Transport Stream has 188-byte Transport Stream (TS) packets. Each TS packet is identified by a particular 13-bit packet identifier (PID). Every audio and video elementary stream is uniquely identified by the PID used in the TS packets that contain them. Additional PIDs contain Program Specific Information (PSI) that includes a Program Association Table (PAT) and a Program Map Table (PMT) which describe the complete transport stream multiplex pattern. Such a multiplex pattern has one or more programs, each of which has one or more elementary streams. Each TS packet has a header and data. The header contains a sync byte, the packet's PID, a four-bit continuity counter together with other information. The elementary streams are encapsulated as Packetized Elementary Streams (PES) before being broken into the TS packets.
What is desired is a compressed video and audio transport stream multiplexer for combining elementary streams and program specific information without burdening a microprocessor with excessive copying.